Method of cathode disintegration



Ffih m, 1915?? w BURKHARDT ET AL 2,148,045

METHOD OF CATHODE DISINTEGRATIQN Filed June 15, 1937 2 Sheets-Sheet l M Burk/14% 9 7? 75 6130 era/$2 lwem Feb.'21; 1939. w. BURKHARDT ET AL METHOD OF GATHODE DISINTEGRATION Filed June 15, 1937 2 Sheets-Sheet 2 V- um 64m? 9 3/261 sake Patented F eb. 21, 1939 UNITED STATES 2,148,045 7 METHOD or CATHODE nrsm'memrron Wilhelm Burkhardt, Berlin-Grunewald, and Rudoli' Reinecke, Berlin-Lankwitz, Germany, assigners to Bernhard Berghaus, Berlin-Lani:-

. witz, Germany Application June 15, 1937, Serial No. 148,385

In Germany June 17, 1936 v 6 Claims.

When a cathode is heated up by the application of electrical energy, magnetic fields are necessarily produced, which, as has been experimentally ascertained, have an unfavourable cffeet on the disintegration of the cathode. The ions produced in the filling gas are so deflected by the magnetic field in their direction towards the cathode surface, that their disintegrating effect is substantially reduced.

Moreover, it has been experimentally ascertained, that continuous disintegration, owing to the material being, disintegrated by the vvcontinuously acting ion bombardment, produces an increased density in the immediate proximity of the cathode surface. The increased. density in front of the cathode causes. that a portion of the ions which are directed towards the cathode and are accelerated, parts with its energy when striking against the disintegrated particles, with- 2 out being effectiveas regards the disintegration.

The disadvantages referred to are avoided by the present invention.

The invention relates to a method of cathode disintegration in which the cathode is preheated 25 and it consists in that the heating up of the cathode and its disintegration are eifected alternately. If in the case of cathode disintegration, the cathode is heated up by an intermittent supply of energy, then a larger amount is released 39 from the material of the cathode, as compared with the heating up by a continuous supply of energy, assuming the .energy to be the same. During the period of interruption of the supply of energy, the ions can impinge unhindered on 35 the cathode material heated almost up to the vaporization point. If the disintegrated amounts of a cathode heated: firstly, only by the glow current; secondly, by afcontinuous supply of energy; and thirdly, by an intermittent supply 40 of energy, are compared with one another, it is foundthat with a continuous supply of energy,

the amount disintegrated is smaller, and with an interrupted supply, greater, than the amount alone.

Moreover, more material is disintegrated from 50 rupting the ionization, the greater density of the particles formed in front of the cathode can be equalized into space owing to increased diffusion. After renewed ion bombardment, owing to the new smaller density of the disintegrated llmaterial in front of the cathode, a larger amount disintegrated obtainable by the glow current of a continuous current.

can be obtained, before the increased density is again established. By the joint use of these two phenomena which have an improved effect, in such a manner that the disintegration takes place during the periods of rest of the heating, an especially improved efficiency of cathode disintegration is obtained.

The invention also relates to a method of coating metallic or non-metallic articles with layers of metals or metalloids or non-metals by cathode w disintegration, in which the cathode is additionally heated, and a further feature of the invention consists in that the additional heating of the cathode is effected periodically alternating with the disintegration. The periods may be chosen as desired. By the periodic alternating heating and disintegration one of the advantages secured is that, during the disintegration, no disturbing fields of the heating current are pres-' ent, so that the disintegration takes place unhindered and, by the additional heating, a substantial increase in the amount disintegrated per. unit of time is-obtained.

The periodic heating and disintegration of the cathode may be effected by the alternating opening and closing of the heating circuit and of the disintegrating circuit. The alternating opening and closing of the heating circuit and of the disintegrating circuit may be effected by means of switches operated by hand, or preferably by mechanical control means, such as controllers,

or by electrical control means such as relays and tube switches.

The periodic heating and disintegration of the cathode may further be eifected with the two circuits permanently closed, in such a manner that a periodic heating current and a periodic disintegrating voltage are employed, the phases of which are relatively displaced. The phase displacement of the heating current and of the disintegrating current may beregulated in such a manner that the maxima of the heating current occur approximately when the disintegrating voltage reaches the minima. The periodic heating of the cathode may be effected by means The continuous current for the heatingof the cathode may preferably consist of a pulsating. continuous current,

via, a continuous current which is superposed to an alternating current voltage mittent direct current.

The periodic heating of the cathode may also be effected by meansof an alternating current. The alternating current for the heating of the cathode may consist of an alternating current of v55 or an interover 50-60 periods, preferably a medium or a high frequency current of 200-10000 periods.

The periodic disintegration may be effected by means of a directcurrent or a direct current voltage. The direct current voltage for the disintegration may preferably consist of a pulsating or intermittent direct current voltage.

' The periodic disintegration may also advantageously be effected by means of a rectified alternating current voltage.

The invention further relates to an apparatus for carrying the method hereinbefore described into effect, and which consists of a vacuum vessel comprising a disintegration chamber with an additional cathode capable of being heated, magnetic fields for holding together and controlling the disintegrated parts of the current and a treatment chamber separably connected thereto for the article to be coated, of a heating circuit and a disintegrating circuit connecting the cathode with the anode, as well as of means for alternately interrupting the two circuits. Controllers or relay switches: may be used for controlling the heating circuit and the disintegrating circuit. A further feature of the invention consists in means for controlling the heating and disintegrating circuits which are coupled together. Use may be made of tuning means, such as self-inductances, capacitiesor resistances, in the disintegrating circuit or heating circuit, to regulate the phase displacement between the heating current and the disintegrating current.

Various modes of carrying the invention into effect are illustrated 'ditically, and by way of example, in the accompanying drawings, in which:

Figure 1 shows the general arrangement for coating metallic or non-metallic articles with layers of metals or metalloids or non -metals by cathode disintegration, in which the cathode is additionally heated;

Figures 2, 3, 4 and 5 show control means for the heating circuit and the disintegrating circuit, the right-hand side of each figure showing the dennection for the heating, and the left-hand side the connection for thedisintegration, and

V Figure 2 showing more particularly the control by means of a controller, Figure 3 the control by means of a relay switch,

Figure 4 the control by means ofa tube switch and Figure 5 an arrangement for the regulation of the phase displacement. I

Referring to Figure 1, l is a vacuum vessel consisting of a disintegrating .chamber 2 and a treatchamber in a removable manner, by means of a ground 6, the heating current being supplied thereto from a source of current I over the adjustable resistance 0 and switch 0.

by means of which the particles disintegrated from the cathode 8 are held together in the form ofacurrentofparticles Il,which producesthe layer ll onthe article l2tobecoated. Thefield coil ll issuppliedwith current from asource ll mpplyotgssand Ilashortpipetobecannected' I. is a field coil for the production of the magnetic field to the vacuum pump. The switches 8 and 2| are, for instance, operated alternately.

Referring to Figure 2, which illustrates the use of a controller for controlling the heating and the disintegration, 24 is the controller for the interruption of the heating current, and 25 the con troller for the interruption of the disintegrating voltage. These controllers are substituted for the switches 9 and 2| shown in Figure 1. The two controllers are driven together and are adjustable relatively to one another, for instance, by means of a motor 26. The controller 24 for the heating current consists of two discs of insulating material aranged next to one another and provided on their periphery with contact segments 21 and 28 which are adjustable relatively to one another for the purpose of regulating the period of heating. Similarly, the controller 25 for the disintegrating voltage consists of two discs of insulating material arranged next to one another and provided on their periphery with contact segments 29 and 30, which are adjustable relatively to one another for the purpose of regulating the period of disintegration.

'Referring to Figure 3, illustrating ,a relay arrangement for the control of the heating and the disintegration, the switch 3| in the heating circuit is controlled by an electromagnet 32 and the switch 33 in the disintegrating circuit by an electromagnet 34. The control current for the electromagnets may be controlled by means of controllers, as in the case of the arrangement shown in Figure 2.

Referring to Figure 4, which illustrates a thermionic tube connection between the heating and the disintegrating circuit, 35 is the heating circuit and 36 the disintegrating circuit. The thermionic switch tube 31 is inserted in the heating circuit and the thermionic switch tube 38 in the.

disintegrating circuit, the cathodes of which are connected together and to the secondary of a transformer 39. The grids of the switch tubes 21 and 28 are connected together over the secondary winding 40 of the transformer. The primary winding ll of the transformer is connected for the purpose of the control to an alternating current, the frequency of which may be chosen as required.

Referring to Figure 5, which illustrates an arrangement for regulating the phase displacement of the heating current with respect to the disintegrating current, 42 is a transformer which may,

for instance, be connected to a supply of alternating current 43 for the heating current, and H is a second transformer connected to the supply current for the disintegrating voltage. The disintegrating circuit also includes an adjustable condenser 45, a self-inductance 46, and a resistance 41, for the purpose of regulating the phase 1. A method of metallisation by cathode disintegration, consisting in that the cathode is first heated and is then alternately heated and disintegrated by two separate currents applied alternately and repeatedly thereto until the required thickness of metal coating is'obtained.

2. A method of metallisation by cathode dis integration, consisting in that the cathode is first heated and is then alternately and repeatedly heated and disintegrated by alternately and repeatedly opening and closing the heating circuit and the disintegrating circuit.

3. A method of metallisation by cathode disf 2,148,045 integration, consisting in that the cathode is first heated and is then alternately and repeatedly heated and disintegrated by alternately and repeatedly opening and closing the heating circuit and the disintegrating'circuit automatically.

4. A method of metallisation by cathode disintegration consisting in that the cathode is first heated and is then alternately heated and disintegrated by two separate periodic currents applied repeatedly thereto until the required thickness of metal coating is obtained, the said two separate periodic currents having a phasedisplacement so regulated that the maxima of the heating current occur approximately when the disintegrating voltage reaches its minima.

5. A method as claimed in claim 1, in which the alternate heating of the cathodes is eflected by means of an alternating current.

6. A method as claimed in claim 1, in which the alternate heating is eflected by means ofan alternating current of high frequency.

wmmu nunxmam'. RUDOLF amen. 

